The calcium-binding domain of the stress protein SEP53 is required for survival in response to deoxycholic acid-mediated injury
The calcium-binding domain of the stress protein SEP53 is required for survival in response to deoxycholic acid-mediated injury
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DOI：
10.1111/j.1742-4658.2006.05206.x
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发表时间：
2006-05-01
期刊：
影响因子：
5.4
通讯作者：
Hupp, TR
中科院分区：
文献类型：
--
作者：
Darragh, J;Hunter, M;Hupp, TR
应激蛋白反应在一定程度上是作为一种机制来保护细胞免受环境破坏剂的毒性影响。食道鳞状上皮细胞进化出一种非典型的应激反应，导致合成一种功能不明的53 kDa蛋白，称为鳞状上皮诱导的53 kDa应激蛋白(SEP53)。鉴于脱氧胆酸(DCA)在鳞状上皮中作为潜在的损伤剂的作用，我们开发了测量DCA对SEP53介导的损伤反应的影响的方法。为了实现这一点，我们克隆了人SEP53基因，开发了一组针对该蛋白的单抗，并表明SEP53的表达主要限于鳞状上皮。克隆形成实验表明，SEP53在哺乳动物细胞系中可以作为一种生存因子发挥作用，可以减轻DCA诱导的细胞死亡。并能减弱DCA介导的细胞内游离钙的增加。SEP53中高度保守的EF-Hand钙结合结构域的缺失中和了该蛋白的菌落存活活性，中和了SEP53在DCA暴露后的保护作用，并允许钙离子升高以响应DCA的攻击。这些数据表明，鳞状细胞应激蛋白SEP53可以作为DCA介导的钙内流的修饰物，并识别一条新的生存途径，其研究可能有助于阐明与鳞状细胞损伤和相关癌症发展相关的机制。
Stress protein responses have evolved in part as a mechanism to protect cells from the toxic effects of environmental damaging agents. Oesophageal squamous epithelial cells have evolved an atypical stress response that results in the synthesis of a 53 kDa protein of undefined function named squamous epithelial-induced stress protein of 53 kDa (SEP53). Given the role of deoxycholic acid (DCA) as a potential damaging agent in squamous epithelium, we developed assays measuring the effects of DCA on SEP53-mediated responses to damage. To achieve this, we cloned the human SEP53 gene, developed a panel of monoclonal antibodies to the protein, and showed that SEP53 expression is predominantly confined to squamous epithelium. Clonogenic assays were used to show that SEP53 can function as a survival factor in mammalian cell lines, can attenuate DCA-induced apoptotic cell death,. and can attenuate DCA-mediated increases in intracellular free calcium. Deletion of the highly conserved EF-hand calcium-binding domain in SEP53 neutralizes the colony survival activity of the protein, neutralizes the protective effects of SEP53 after DCA exposure, and permits calcium elevation in response to DCA challenge. These data indicate that the squamous cell-stress protein SEP53 can function as a modifier of the DCA-mediated calcium influx and identify a novel survival pathway whose study may shed light on mechanisms relating to squamous cell injury and associated cancer development.